System for delivering stents to bifurcation lesions

ABSTRACT

A stent deployment catheter includes an elongate catheter shaft having a proximal end, a distal end, and a lumen therethrough. A first stent sheath has a lumen therethrough and an elongate longitudinal opening therein. A second stent sheath also has a lumen therethrough and an elongate longitudinal opening therein. The first and second stent sheaths are disposed at the distal end of the catheter shaft. An elongate actuator is coupled to the first and second stent sheaths and extends to a proximal region of the catheter shaft. The actuator is longitudinally movable relative to the catheter shaft.

BACKGROUND OF THE INVENTION

The present invention relates to a system for treating vascular disease.More specifically, the present invention relates to a system fordeploying a stent in a bifurcation lesion.

Vascular disease currently represents a prevalent medical condition.Typical vascular disease involves the development of a stenosis in thevasculature. The particular vessel containing the stenosis can becompletely blocked (or occluded) or it can simply be narrowed (orrestricted). In either case, restriction of the vessel caused by thestenotic lesion results in many well known problems caused by thereduction or cessation of blood circulation through the restrictedvessel.

A bifurcation is an area of the vasculature where a first (or parent)vessel is bifurcated into two or more branch vessels. It is not uncommonfor stenotic lesions to form in such bifurcations. The stenotic lesionscan affect only one of the vessels (i.e., either of the branch vesselsor the parent vessel) two of the vessels, or all three vessels.

Vascular stents are also currently well known. Vascular stents typicallyinvolve a tubular stent which is movable from a collapsed, low profile,delivery position to an expanded, deployed position. The stent istypically delivered using a stent delivery device, such as a stentdelivery catheter. In one common technique, the stent is crimped down toits delivery position over an expandable element, such as a stentdeployment balloon. The stent is then advanced using the catheterattached to the stent deployment balloon to the lesion site under anysuitable, commonly known visualization technique. The balloon is thenexpanded to drive the stent from its delivery position to its deployedposition in which the outer periphery of the stent frictionally engagesthe inner periphery of the lumen. In some instances, the lumen ispredilated using a conventional dilatation catheter, and then the stentis deployed to maintain the vessel in an unoccluded, and unrestrictedposition.

Self-expanding stents can also be used. Self-expanding stents aretypically formed of a resilient material. The resilient material hassufficient resilience that it can be collapsed to the low profileposition and inserted within a delivery device, such as a catheter. Oncethe catheter is placed at the site of the stenotic lesion, the stent ispushed from within the catheter such that it is no longer constrained inits low profile position. The stent, driven by the resilience of thematerial, expands to a higher profile, deployed position in which itsouter periphery frictionally engages the walls of the stenosed vessel,thereby reducing the restriction in the vessel.

While there have recently been considerable advances in stent design andstent deployment techniques, current methods of treating bifurcationlesions are suboptimal, particularly where both downstream branchvessels are affected by the lesion. Current techniques of dealing withsuch lesions typically require the deployment of a slotted tube stentacross the bifurcation. However, this compromises the ostium of theunstented branch.

Further, once the first stent is deployed, the treating physician mustthen advance a dilatation balloon between the struts of the stentalready deployed in order to dilate the second branch vessel. Thephysician may then attempt to maneuver a second stent through the strutsof the stent already deployed, into the second branch vessel fordeployment. This presents significant difficulties. For example,dilating between the struts of the stent already deployed tends todistort that stent. Further, deploying the second stent through thestruts of the first stent is not only difficult, but it can also distortthe first stent. Thus, the current systems used to alternately deploystents in a bifurcated lesion have significant disadvantages.

SUMMARY OF THE INVENTION

A stent deployment catheter includes an elongate catheter shaft having aproximal end, a distal end, and a lumen therethrough. A first stentsheath has a lumen therethrough and an elongate longitudinal openingtherein. A second stent sheath also has a lumen therethrough and anelongate longitudinal opening therein. The first and second stentsheaths are disposed at the distal end of the catheter shaft. Anelongate actuator is coupled to the first and second stent sheaths andextends to a proximal region of the catheter shaft. The actuator islongitudinally movable relative to the catheter shaft.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates typical bifurcation lesion.

FIG. 2 illustrates one embodiment of a stent delivery system inaccordance with one aspect of the present invention.

FIG. 2A illustrates a stent deployment sheath in accordance with oneaspect of the present invention.

FIG. 3 illustrates placement of a distal end of the stent deliverysystem shown in FIG. 2 at a site of a bifurcation lesion.

FIG. 4 illustrates deployment of stents in the bifurcation using thesystem shown in FIGS. 2 and 3.

FIG. 5 illustrates an articulated stent.

FIG. 6 illustrates the distal end of a stent deployment system locatedat a bifurcation.

FIG. 7 illustrates deployment of the stents using the system shown inFIG. 6.

FIG. 8 illustrates an articulated stent positioned in the bifurcationshown in FIGS. 6 and 7.

FIG. 9 illustrates another embodiment of a stent deployment system inaccordance with one aspect of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 1 illustrates bifurcation 10 which includes parent vessel 12, firstbranch vessel 14 and second branch vessel 16. FIG. 1 also illustratesthat a bifurcation lesion 18 has developed in bifurcation 10. Lesion 18extends into both branch vessels 14 and 16, and extends slightly intoparent vessel 12 as well. In order to treat bifurcation lesion 18, itmay commonly first be predilated with a conventional balloon catheterdilatation device.

FIG. 2 illustrates a stent deployment system 20 in accordance with oneaspect of the present invention. System 20 includes catheter 22 whichhas proximal portion 24, distal portion 26 and lumen 28 extendingtherethrough. In one embodiment, proximal portion 24 includes aconventional proximal hub and a pair of guidewire tubes 30 and 32, whichdefine guidewire lumens extending from the proximal end of catheter 22to its distal end 26. System 20 is illustrated, in FIG. 2, with a pairof guidewires 34 and 36 extending through the guidewire lumens definedby tubes 30 and 32. Guidewire tube 30 includes a bumper 130 disposed atits distal end. In a similar manner, guidewire tube 32 includes bumper132 connected at the distal end thereof. Bumpers 130 and 132 aredimensioned so as to abut the proximal ends of the stents 46 and 48,discussed hereafter.

System 20 also, in one illustrative embodiment, includes proximalactuator 38 which is coupled to actuation wire 40. Actuation wire 40extends from the proximal end of catheter 22 to a distal region ofcatheter 22 where it is coupled to a pair of stent deployment sheaths 42and 44. of course, an additional actuation wire 41 (shown in phantom inFIG. 2) can also be provided, in which case wire 40 is coupled to sheath42 and wire 41 is coupled to sheath 44.

In either case, each of stent deployment sheaths 42 and 44 has aproximal end and a distal end. A pair of stents, 46 and 48, areillustrated in FIG. 2 positioned within the distal end of sheaths 42 and44, respectively.

FIG. 2A illustrates one embodiment of stent deployment sheath 42. Itwill be appreciated that sheath 44 is formed substantially the same assheath 42. Therefore, only sheath 42 is described in detail in FIG. 2A.Sheath 42 includes proximal end 50 and distal end 52 and is formedsubstantially cylindrically, but with an elongate slot, or separation,54 extending from its proximal end 50 to its distal end 52. Sheath 42has a longitudinal length sufficient to hold stent 46 in a distalportion thereof. Sheath 42 is also sized to slidably fit within lumen 28of catheter 26. Sheath 42 is preferably formed of a resilient material.The resilience of the material is such that it is sufficient to maintaina stent (such as stent 46) therein in a collapsed, low profile position.However, sheath 42 is also sufficiently resilient that it can beexpanded such that slit 54 opens slightly to receive a guidewire and astent articulation element to accommodate deployment of the stentcontained therein, as will be described later in the specification.

Referring again to FIG. 2, sheaths 42 and 44 are generally coaxiallydisposed at their proximal ends about guidewire tubes 30 and 32.However, the distal ends of sheaths 42 and 44 are not coaxially disposedrelative to one another. Rather, the distal end of sheath 44 extendsout, through the slot 54 in stent 46 such that the distal ends ofsheaths 42 and 44 can independently track guidewires 34 and 36 whichextend therethrough.

Guidewire 34 extends out through the distal end of guidewire tube 30,through the slit 54 in sheath 20 44, through stent 46, and into branchvessel 14. Guidewire 36 extends out through the distal end of lumen 32,through stent 48 and sheath 44, and into branch vessel 16.

Stents 46 and 48 are illustrative self-expanding stents. Stents 46 and48 are thus formed of a resilient material which can be collapsed into alow profile, delivery position, shown in FIG. 2. When in the collapsedposition shown in FIG. 2, stents 46 and 48 exert an outward pressure onthe inner wall of sheaths 42 and 44, respectively, such that stents 46and 48 are frictionally held within sheaths 42 and 44 during delivery.Stents 46 and 48 also have sufficient resilience that they self-expand,when removed from sheaths 42 and 44, respectively, to a high profiledeployed position. Stents 46 and 48 can be formed as two separatestents, or can optionally be formed as an articulated stent havingportions 46 and 48 connected by articulation element 56.

In operation, guidewires 34 and 36 are first advanced to the positionsshown in FIG. 2 such that guidewire 34 is advanced across lesion 18 inbranch vessel 14 and guidewire 36 is advanced across lesion 18 in branchvessel 16. Stents 46 and 48 are then collapsed to their low profileposition and inserted within the distal end of sheaths 42 and 44.Preferably, stents 46 and 48 have been previously collapsed and loadedinto position by the manufacturer. Catheter 22 (including sheaths 42 and44 and guidewire tubes 30 and 32) is either backloaded or preloaded,onto guidewires 34 and 36. Catheter 22 is then advanced within thevasculature to a position just proximal of bifurcation 10, asillustrated in FIG. 2.

FIG. 3 illustrates the next step in deploying stents 46 and 48 in branchvessels 14 and 16. Catheter 22 is advanced beyond the position shown inFIG. 2 such that the distal ends 52 of sheaths 42 and 44 track alongguidewires 36 and 38, respectively. This causes the distal ends 52 ofsheaths 42 and 44 to be advanced within branch vessels 14 and 16 to theposition shown in FIG. 3. In one preferred embodiment, catheter 22 isadvanced distally until the distal ends of guidewire tubes 30 and 32reside closely adjacent the proximal ends 50 of stents 46 and 48.

Actuator 38 (shown in FIG. 2) is then withdrawn proximally to exert aproximally directed force on actuator wire 40 in a direction indicatedby arrow 60. This causes sheaths 42 and 44 to be withdrawn proximally aswell. As the sheaths 42 and 44 are withdrawn proximally, bumpers 130 and132 abut the proximal end of the stents 46 and 48 and thereby maintaintheir longitudinal position. Thus, as the sheaths 42 and 44 arewithdrawn proximally, the guidewire tubes 30 and 32 extend out thedistal end of the sheaths 42 and 44 thereby releasing stents 46 and 48from the low profile, constraint position shown in FIG. 3. Stents 46 and48 thus expand to frictionally engage the inner walls of branch vessels14 and 16.

As sheaths 42 and 44 are withdrawn proximally, the entire longitudinalextent of stents 46 and 48 become unconstrained by the sheaths and thusexpand to engage the inner walls of branch vessels 14 and 16, and to bedeployed therein, as shown in FIG. 4. Also, as the sheaths are withdrawnproximally, the outer surfaces of sheaths 42 and 44 engage the innersurface of lumen 28. Thus, sheath 44 is forced through the slit 54 insheath 42 until the two sheaths are fully coaxially disposed. Once inthis position, as shown in FIG. 4, catheter 22 is withdrawn overguidewires 34 and 36, leaving stents 46 and 48 deployed in branchvessels 14 and 16.

FIG. 5 illustrates one embodiment of stents in accordance with oneaspect of the present invention in which stents 46 and 48 are notseparate stents, as shown in previous figures, but are instead portionsof an articulated stent connected by articulation element 56. As withstents 46 and 48 in FIGS. 2-4, the stent portions shown in FIG. 5 arealso preferably self-expanding stents which can be collapsed to a lowprofile, delivery position, but are sufficiently resilient such that,when unconstrained, they expand to a higher profile, deployed position.In such an embodiment, sheaths 42 and 44 need not be coaxially disposedwithin lumen 28 of shaft 26, but can be disposed in a side-by-sidemanner, as described below.

FIG. 6 illustrates an embodiment of the deployment system 62 inaccordance with one aspect of the present invention in which the stentbeing delivered is an articulated stent such as that shown in FIG. 5. Anumber of the items of system 62 are similar to those of system 20, andare correspondingly numbered. System 62 is prepared and advanced to theposition just proximal of bifurcation 10 (shown with respect to system20 in FIG. 2) in the same fashion as system 20. Catheter 22 is thenadvanced such that the distal end of sheaths 42 and 44 track overguidewires 36 and 34, respectively, until they reside within branchvessels 16 and 14, respectively. Actuator 38 (shown in FIG. 2) is thenwithdrawn proximally such that actuator wire 40 is also drawnproximally. This causes sheaths 42 and 44 to be withdrawn proximally,along with stents 46 and 48, until articulation element 56 abuts thedistal ends of guidewire tubes 30 and 32. Continued proximal withdrawalof sheaths 42 and 44 causes slits 54, therein, to receive articulationelement 56 and any septum, or junction, between guidewire tubes 30 and32. This allows articulation element 56 to slide within slots 54 assheaths 42 and 44 are withdrawn proximally, while leaving stents 46 and48 in place.

FIG. 7 illustrates system 62 with sheaths 42 and 44 withdrawn proximallya short distance, exposing a distal portion of stents 46 and 48 to theinner walls of branch vessels 16 and 14, respectively. Upon beingunconstrained by sheaths 42 and 44, stents 46 and 48 self-expand to thehigher profile, deployed position.

FIG. 8 illustrates system 62 with sheaths 42 and 44 fully withdrawnwithin catheter 26 leaving stents 46 and 48 deployed in branch vessels16 and 14, respectively. It should be noted that sheaths 42 and 44 neednot be coaxially arranged, even when withdrawn within shaft 26. Instead,slits 54 simply expand to receive the septum between guidewire tubes 30and 32 or are otherwise separately longitudinally aligned within shaft26. Catheter 22 is then withdrawn from the vasculature leaving thedeployed stents 46 and 48 in place. Guidewires 34 and 36 are thenwithdrawn from the vasculature. of course, guidewires 34 and 36 can bewithdrawn simultaneously with catheter 22, as well.

FIG. 9 illustrates another embodiment of a catheter 70 in accordancewith one aspect of the present invention. A number of items are similarto catheter 22 shown in FIG. 2, and are similarly numbered. However,rather than guidewire tubes 30 and 32 extending from a distal end ofshaft 26 all the way to a proximal end of catheter 70, guidewire tubes30 and 32 have proximal openings located in a distal region of shaft 26.Thus, it can be seen that the present invention can be implemented in asingle operator exchange type configuration as well.

As can be seen, the present invention provides an improved system andtechnique for deploying stents at bifurcation lesions. The presentinvention provides deployment sheaths configured to allow convenient andaccurate placement of stents, over two guidewires, without removing theguidewires from the vasculature, and without a great deal of excessmanipulation required by the treating physician.

Although the present invention has been described with reference topreferred embodiments, workers skilled in the art will recognize thatchanges may be made in form and detail without departing from the spiritand scope of the invention.

What is claimed is:
 1. A stent deployment system, comprising:a catheterhaving a proximal end, a distal end, a delivery lumen extending throughat least a distal portion thereof, and first and second guide wirelumens extending at least through the distal portion thereof; a firstsheath portion including a first tubular wall having a proximal end, adistal end and a longitudinal opening extending proximally from thedistal end thereof, the longitudinal opening being sized to receive aguide wire therethrough, the first tubular wall having an innerperiphery sized to receive a collapsible stent in a collapsed position;a second sheath portion including a second tubular wall having aproximal end, a distal end and a longitudinal opening extendingproximally from the distal end thereof, the longitudinal opening beingsized to receive a guide wire therethrough, the second tubular wallhaving an inner periphery sized to receive a collapsible stent in acollapsed position; and an actuator, coupled to the first and secondsheath portions, longitudinally movable relative to the catheter,comprisinga first elongate member coupled to the first sheath portionand extending through the delivery lumen to a proximal end thereof and asecond elongate member coupled to the second sheath portion andextending through the delivery lumen to a proximal end thereof.
 2. Thestent deployment system of claim 1 wherein the first and second tubularwalls are sized to receive first and second stent portions of anarticulated stent therein, and wherein the longitudinal openings in thefirst and second tubular walls are sized to receive an articulationelement connecting the first and second stent portions.
 3. The stentdeployment system of claim 1 wherein the longitudinal opening in thefirst tubular wall is formed to receive at least a portion of the secondtubular wall therethrough upon exertion of an actuation force on theactuator sufficient to cause the first and second sheath portions tomove within the delivery lumen.
 4. The stent deployment system of claim1 and further comprising:a first guidewire extending through the firstguidewire lumen and through the longitudinal opening in the firsttubular wall and out the distal end of the first tubular wall.
 5. Thestent deployment system of claim 4 and further comprising:a secondguidewire extending through the second guidewire lumen and through thelongitudinal opening in the second tubular wall and out the distal endof the second tubular wall.
 6. A method of stenting a bifurcation havinga parent vessel and first and second branch vessels,comprising;positioning a first guide wire in the first branch vessel;positioning the second guide wire in the second branch vessel; providinga catheter having a delivery lumen and first and second guide wirelumens; providing first and second sheaths, each having a longitudinalopening therein and a stent retaining lumen with a collapsible stenttherein; positioning the first sheath over the first guide wire suchthat the first guide wire extends through the longitudinal opening inthe second sheath, through the stent and out the distal end of the firstsheath and such that the proximal end of the first sheath is within thedistal end of the delivery lumen; positioning the second sheath over thesecond guide wire such that the second guide wire extends through thelongitudinal opening in the first sheath, through the stent and out thedistal end of the second sheath and such that the proximal end of thesecond sheath is within the distal end of the delivery lumen; advancingthe catheter over the first and second guide wires until the distal endsof the first and second sheaths are in the first and second branchvessels, respectively; and exerting a proximally directed force on anactuator element, the actuator element coupled to a proximal end of thewire, the wire coupled to the first and second sheaths through thedelivery lumen.
 7. The method of claim 6 and furthercomprising:withdrawing the catheter with the first and second sheaths inthe delivery lumen.
 8. A stent deployment catheter, comprising:anelongate catheter shaft having a proximal end, a distal end and a lumentherethrough; a first stent sheath having a lumen therethrough and anelongate longitudinal opening therein and being disposed at the distalend of the catheter shaft; a second stent sheath having a lumentherethrough and an elongate longitudinal opening therein and beingdisposed at the distal end of the catheter shaft; and an elongateactuator comprising, a first elongate actuator member coupled to thefirst stent sheath and a second elongate actuator member coupled to thesecond stent sheath, the actuator coupled to the first and second stentsheaths and extending to a proximal region of the catheter shaft, theactuator being longitudinally moveable relative to the catheter shaft.9. The stent deployment catheter of claim 8 wherein proximal ends of thefirst and second stent sheaths are coaxially positioned within thedistal end of the catheter shaft.
 10. The stent deployment catheter ofclaim 8 wherein proximal ends of the first and second stent sheaths arepositioned in side-by-side arrangement within the distal end of thecatheter shaft.
 11. The stent deployment catheter of claim 8 wherein thefirst and second stent sheaths are sized to receive first and secondcollapsible stent portions therein, respectively, wherein the first andsecond stent portions are connected by an articulation element andwherein the longitudinal openings in the first and second stent sheathsare sized to receive the articulation element therethrough.
 12. Thestent deployment catheter of claim 8 wherein the catheter shaftcomprises:first and second guidewire lumens extending at least throughthe distal end thereof.
 13. The stent deployment catheter of claim 12wherein the longitudinal openings of the first and second stent sheathsare sized to receive first and second guidewires therethrough.
 14. Thestent deployment catheter of claim 13 wherein the longitudinal openingin the first stent sheath is expandable to receive an outer periphery ofthe second stent sheath therethrough.
 15. A method of stenting abifurcation having a parent vessel and first and second branch vessels,comprising;positioning a first guide wire in the first branch vessel;positioning the second guide wire in the second branch vessel; providinga catheter having a delivery lumen and first and second guide wirelumens; providing collapsible stents comprise first and second portionscoupled to one another by an articulation element; providing first andsecond sheaths, each having a longitudinal opening therein and a stentretaining lumen with a collapsible stent therein, and wherein providingfirst and second sheaths comprises providing the stent portions in thefirst and second sheaths such that the articulation element extendsthrough the longitudinal openings in the first and second sheaths;positioning the first sheath over the first guide wire such that thefirst guide wire extends through the longitudinal opening in the secondsheath, through the stent and out the distal end of the first sheath andsuch that the proximal end of the first sheath is within the distal endof the delivery lumen; positioning the second sheath over the secondguide wire such that the second guide wire extends through thelongitudinal opening in the first sheath, through the stent and out thedistal end of the second sheath and such that the proximal end of thesecond sheath is within the distal end of the delivery lumen; advancingthe catheter over the first and second guide wires until the distal endsof the first and second sheaths are in the first and second branchvessels, respectively; and withdrawing the first and second sheathsproximally over the first and second guide wires and into non-coaxialarrangement within the delivery lumen such thatthe longitudinal openingsin the first and second sheaths receive the first and second guide wirelumens and slide thereover as the first and second sheaths are withdrawnproximally and the articulation element passes distally through thelongitudinal openings in the first and second sheaths as the first andsecond sheaths are withdrawn to deploy the stents from within the stentretaining lumens.
 16. The method of claim 15 wherein proximallywithdrawing further comprises:withdrawing the first and second sheathsinto coaxial arrangement within the delivery lumen.
 17. The method ofclaim 16 wherein proximally withdrawing further comprises:withdrawingthe first and second sheaths into the delivery lumen such that thelongitudinal opening in the first sheath receives an outer periphery ofthe second sheath therein.
 18. The method of claim 17 wherein proximallywithdrawing further comprises:withdrawing the first and second sheathssuch that the second sheath passes through the longitudinal opening inthe first sheath as the first and second sheaths are withdrawn until thesecond sheath resides coaxially within the first sheath in the deliverylumen.